Hydraulic jack



g- 23, 1966 H. B. CHAMBERS 3,267,818

HYDRAULIC JACK Filed March 9, 1964 2 Sheets-Sheet 1 I l L I ,1- 74INVENTOR. MEX/EV i O/WKMJ %2; h ilw Aug. 23, 1966 H- B. CHAMBERSHYDRAULIC JACK 2 Sheets-Sheet 2 Filed March 9, 1964 Avian/14 UnitedStates Patent 3,267,818 HYDRAULIC JACK Henry B. Chambers, Santa Barbara,Calif, assignor to Lear Siegler, Inc., El Segundo, Calif., a corporationof Delaware Filed Mar. 9, 1964., Ser. No. 350,381 6 Claims. (Cl. 9Z17)This invention relates to hydraulic jacks which have a safety lockoperable upon a loss of hydraulic pressure.

The hydraulic jack is used extensively in many industries today toelevate weights of considerable magnitude. It is often desirable toretain an elevated load in position for extended periods without alowering of the hydraulic jack. The need for a safety lock on hydraulicjacks is quite apparent for the safety of individuals working about thejack and the load, and for this reason there are a number of known lockswhich are actuated automatically with a loss of fluid pressure. Theknown safety locks have disadvantages which limit the use of the type ofload which may be safely placed upon the hydraulic jack knowing that aloss of fluid pressure is entirely possible.

The known safety locks used in combination with hydraulic jacks haveused such things as sliding ratchets, locking balls, or pins whichprevent movement of the ram with relation to the jack cylinder. Onedisadvantage in using a safety lock is the usual requirement ofphysically releasing the lock which causes some difiiculty in resettingthe jack. Another disadvantage of a ratchet-type safety lock is that itpermits the ram to slip a finite amount after pressure failure beforethe ram is locked against additional movement. Further, the ratchet orsimilar type locks, must be reset against the force of the load restingon the jack, which can be diflicult unless the load is removed.

A severe limiting weakness of the prior art safety locks lies in theparticular size and arrangement of the lock, since the particular areaof the lock limits the size of load which may safely be supported by thejack. It must be presumed that the largest load subjected upon the jackwill at some time be supported by the safety lock, and in a great manycases, the size of the prior art ratchet pin, or ball type safety lockshave been considerably smaller than the supporting ram, piston, orcylinder arrangement for the entire jack, which inherently unduly limitsthe size of a load safely carried by the safety lock portion of thejack.

In accordance with my present invention, I have eliminated many of theundesirable features and disadvantages of the prior art hydraulic jacksafety locks. I provide a safety lock which automatically issubstantially instantaneously engaged with a loss of fluid pressure uponthe jack and is equally automatically disengaged with the recovery offluid pressure. Thus, there is virtually no slip-page or jerking with mylook as occurs with ratchettype locks. The particular arrangement of thesafety lock constructed according to my invention allows a maximum loadto be supported by the lock, and the supporting elements include the ramand the cylinder, thus performing dual functions with a minimum numberof parts. Addition-ally, a part of the safety lock includes a stop forthe piston which further increases the usefulness of my invention.

A hydraulic jack constructed according to my invention includes a rammounted on a piston that slides in a cylinder. Pressurized fluid isapplied to one side of the piston to move the ram and a load in a firstdirection. A means for preventing the movement of the ram in a seconddirection after a loss of pressurized fluid is mounted upon the ram andincludes a friction lock, which is urged into an inactive position bythe pressurized fluid.

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The movement preventing means is engageable with the ram in anyposition. A resilient element urges the lock toward an active position.

Other advantages and features of my present invention will becomeapparent after considering the following specification and drawings inwhich:

FIG. 1 is a vertical cross-sectional view of a hydraulic jack having alocking mechanism constructed according to the present invention;

FIG. 2 is a cross-sectional view of the hydraulic jack illustrated inFIG. 1 with the section taken along line 22; and

FIG. 3 is a partial cross-sectional view illustrating a keying mechanismassociated with the lock with the section taken along line 3--3 of FIG.1.

Referring now to all the figures, a hydraulic jack 10 includes avertical cylinder 12 having a piston 14 slidably disposed therein. Athreaded ram 16 is mounted on the top of the piston 14 and extendsupwardly out of the cylinder 12 to engage a load (shown only in phantomline). A friction locking mechanism 18, constructed ac cording to myinvention, allows the ram 16 to move upwardly to lift a load under theforce of a pressurized fluid provided by a pump 20, and with the loss ofpressurized fluid, the locking mechanism automatically holds the ram inplace Without dropping the load.

The cylinder is in the form of a tube having an integrally formed closedbottom 2-2. An opening 24 through the wall of the cylinder 12 is incommunication with a conduit 26 leading from the pump such thatpressurized fluid may flow into the interior of the cylinder 12 to forcethe piston 14 and ram 16 upwardly. The piston 14 is cylindrical in formand has two piston rings 27, 28 mounted near the extremities of thepiston.

The ram 16 is generally cylindrical in shape and has a continuoushelical groove formed along its entire length in the shape of Acmethreads 30.

A ring 3 2 has inwardly directed threads 34, which mate with the threads30 on the ram 16. An annular skirt 36 surrounds the ring 32 and issecured to it by a plurality of bolts 38. An inwardly extending annularflange 40, formed integrally with the bottom of skirt 36, has a lowersurface 40A which abuts the upper end of the cylinder 12. Thus, theskirt 36 attached to ring 32 may support the ram 16 in any positionsince the skirt is supported by the cylinder 12. An insert 42 isattached to the upper end of the cylinder 12 by the threads 43, andincludes an outwardly extending lip 44 which normally abuts the bottomof ring 32 and the top surface of flange 40. With this arrangement, thering 32 and skirt 36 are free to rotate upon axial movement of the ram16, but are prevented from moving in any direction parallel to themovement of the ram. The bottom surface of the lower portion of insert42 which defines threads 43 serves as a positive stop to limit upwardtravel of piston 14 as shown in FIG. 1.

A sleeve 46 is tubular in shape and has an internal annular downwardlydiverging tapered portion 46A formed thereon which mates with anexternal annular downwardly diverging tapered portion 47A on the skirt36. The sleeve 46 is movable axially and normally is held with itstapered portion 46A spaced from the mating tapered portion 47A on theskirt 36. A pair of arcuately shaped keys 48, 49 are attached to theinside diameter of the sleeve 46 by a plurality of bolts. A pair ofarcuately shaped mating keys 50, 51 are attached to the uppermostportion of the cylinder 12. As best illustrated in FIGS. 2 and 3, themating keys 48, 49, 50, and 5 1 occupy the annular space between thecylinder 12 and the sleeve 46. The respective keys are approximatelyapart and are in interlocking relationship to thereby prevent the sleeve46 from rotating with relation to the cylinder 12. As best 15illustrated in FIGS. 1 and 3, the keys 48-51 allow axial movement of thesleeve 46 with relation to the cylinder 12 and the skirt 36.

A second cylinder 52 is in the shape of an annulus having an annularshaped groove 54 formed therein with the lowermost portion of the sleeveextending therein in telescoping relationship. A port 56 formed in thefloor of the groove 54 allows the annular shaped well 57 to be incommunication with the pump 20 by means of a fluid conduit 58. Thus,when the annular Well 57 has pressurized fluid therein, the lowerportion of sleeve 46 is urged upwardly to allow rotation of the ring 32and the skirt 36. A pair of O-ring seals 60, 62 are respectivelyinserted within the cylinder 52 on opposite sides of the lower portionof the sleeve 46.

A pair of outwardly extending triangular shaped ears 64, 66 are weldedto opposite sides of the cylinder 12. A pair of outwardly extendingtriangular shaped ears 68, 70 are welded on opposite sides of the sleeve46 in vertical alignment with ears 64, 66. A pair of tension coilsprings 72, 74 are respectively mounted between ears 64, 68 and 66, 70to urge the sleeve 46 toward contact with the skirt 36 so that themating tapered portion 46A and 47A are in frictional engagement tothereby prevent rotation of the ring 32.

In operation, the hydraulic jack 10, constructed according to my presentinvention, may be inserted beneath a load schematically illustrated inFIG. 1 which may be such things as bridge spans, aircraft frames, andthe like. The pump 20 is energized by an external power source (notshown) to supply pressurized fluid within the cylinder 12 and within theannular well 57. This pressurized fluid moves the piston 14 and ram 16upwardly until the ram abuts the load, and during this movement, thering 32 and skirt 36 are rotated as the ram 16 progressively advancesupwardly. The annular well 57 is also filled with pressurized fluidcausing the sleeve 46 to be urged upwardly against the tension ofsprings 72 and 74 to allow the rotation of ring 32 and skirt 36.

Assuming that the pressurized fluid dispensed by the pump 20 suddenlyfails, the load is no longer supported by the fluid pressure acting onthe piston, but rather by the ram and the ring 32 acting upon the insert42 and the flange portion 40 of the skirt 36 abutting the uppermostportion of the cylinder 12. The loss in pressure within the well 57permits tension springs 72 and 74 to move the sleeve46 downwardly tofrictionally engage the skirt 36. Thus, the construction of the sleeve46 prevents rotation of the ring 32 during those periods when thepressurized fluid does not exert a force upon the piston 14, and the ramis locked against longtiudinal movement.

It should be noted that the tapered mating surface of the skirt 36 andsleeve 46 allow the ram to be locked in any position, not requiringfurther rotation of the ring to perform the locking function.

Once the pressurized fluid again exists beneath the pis ton 14 and well57, the sleeve is raised, the frictional engagement between the sleeve46 and skirt 36 no longer exists, and the load is supported by the fluidpressure.

What is claimed is: 1. In a hydraulic jack including a ram mounted on apiston that is slidably disposed in a cylinder and operated by apressurized fluid subjected on one side of the piston to move the ram ina first direction, the improvement comprising:

the ram has a continuous helical groove formed thereon, a ring rotatablymounted on the ram engages the ram groove, the ring is restrained frommoving with the ram but may freely rotate thereon, the ring includes aportion which abuts the cylinder in supporting fashion, a lock disposedadjacent to the ring, a means for urging the lock out of engagement withthe ring including a second cylinder disposed in telescopingrelationship with the ring,

a fluid conduit communicating with the second cylinder and thepressurized fluid acting on the piston, and means for urging the lookinto engagement with the ring.

2. In a hydraulic jack including a ram mounted on a piston that isslidably disposed in a cylinder and operated by a pressurized fluidsubjected on one side of the piston to move the ram in a firstdirection, the improvement comprising:

the ram having a continuous groove formed thereon,

a ring rotatably mounted on the ram and engaging the ram groove,

the cylinder having a groove formed thereon adjacent the ring,

an inwardly extending flange extending from the ring in lockingrelationship with the cylinder groove,

a lock disposed adjacent the ring,

means for urging the lock out of engagement with the ring when thepressurized fluid is effective upon the piston, and means for urging thelock into engagement with the ring when the cylinder is devoid of fluidpressure.

3. In a hydraulic jack including a ram mounted on a piston that isslidably disposed in a cylinder and operated by a pressurized fluidsubjected on one side of the piston to move the ram in a firstdirection, the improvement comprising:

the ram having a continuous groove formed thereon,

a ring rotatably mounted on the ram and engaging the ram groove,

an outwardly extending flange mounted on the cylinder including a stopportion extending within the cylinder serving to limit the travel of thepiston,

an inwardly extending flange mounted on the ring in locking relationshipwith the cylinder outwardly extending flange,

the inwardly extending flange abutting the cylinder in supportingrelationship,

a friction lock disposed adjacent the ring,

means for urging the lock out of engagement with the ring when thepressurized fluid is effective upon the piston, and

means for urging the lock into engagement with the ring when thecylinder is devoid of fluid pressure.

4. In a hydraulic jack including a ram mounted on a piston that isslidably disposed in a cylinder and operated by a pressurized fluidsubjected on one side of the piston to move the ram in a firstdirection, the improvement comprising:

the ram is threaded along a substantial portion of its length,

a ring having inwardly directed threads thereon engaged with thethreaded ram and rotatable thereon, the cylinder having a groove formedthereon adjacent the ring,

an interlocking lip extending from the ring and extending into thecylinder groove,

a tapered skirt formed on the ring,

a tapered sleeve mating with the tapered ring skirt slidably disposedaround the ring, v

means for urging the sleeve into engagement with the ring skirt andengaging the sleeve, and

means for urging the sleeve out of engagement with the sleeve when fluidpressure is eflective upon the piston in operative engagement with thesleeve.

5. In a hydraulic jack including a ram mounted on a piston that isslidably disposed in a cylinder and operated by a pressurized fluidsubjected on one side of the piston to move the ram in a firstdirection, the improvement comprising:

the ram is threaded along a substantial portion of its length,

a ring having inwardly directed threads thereon engaged with thethreaded ram and rotatable thereon,

the cylinder having a groove formed thereon adjacent the ring,

an interlocking lip extending from the ring and extending into thecylinder groove,

a tapered skirt formed on the ring, I,

a tapered sleeve mating with the tapered ring skirt slidably disposedaround the ring,

a spring means mounted in tension between the sleeve and the cylinder,and

means for urging the sleeve out of engagement with the sleeve when fluidpressure is eifective upon the piston.

6. In a hydraulic jack including a ram mounted on a piston that isslidably disposed in a cylinder and operated by a pressurized fluidsubjected on one side of the piston to move the ram in a firstdirection, the improvement comprising:

the ram is threaded along a substantial portion of its length, a ringhaving inwardly directed threads thereon engaged with the threaded ramand rotatable thereon,

an outwardly extending flange mounted on the cylinder including aportion extending within the cylinder serving as a stop for the piston,

an annulus having a groove formed therein with the sleeve extendingtherein in telescoping relation, and

a conduit in communication with the annular groove and with thepressurized fluid subjected upon the piston.

References Cited by the Examiner UNITED STATES PATENTS 2,632,426 3/1953Geesink 9217 2,773,485 12/1956 Geyer 92l7 2,804,054 8/1957 Geyer 92l73,104,593 9/1963 Clifton et al 92l7 MARTIN P. SCHWADRON, PrimaryExaminer.

25 SAMUEL LEVINE, Examiner.

I. C. COHEN, Assistant Examiner.

1. IN A HYDRAULIC JACK INCLUDING A RAM MOUNTED ON A PISTON THAT ISSLIDABLY DISPOSED IN A CYLINDER AND OPERATED BY A PRESSURIZED FLUIDSUBJECTED ON ONE SIDE OF THE PISTON TO MOVE THE RAM IN A FIRSTDIRECTION, THE IMPROVEMENT COMPRISING: THE RAM HAS A CONTINUOUS HELICALGROOVE FORMED THEREON, A RING ROTATABLY MOUNTED ON THE RAM ENGAGES THERAM GROOVE, THE RING IS RESTRAINED FROM MOVING WITH THE RAM BUT MAYVREELY ROTATE THREON, THE RING INCLUDES A PORTION WHICH ABUTS THECYLINDER IN SUPPORTING FASHION, A LOCK DISPOSED ADJACENT TO THE RING, AMEANS FOR URGING THE LOCK OUT OF ENGAGEMENT WITH THE RING INCLUDING ASECOND CYLINDER DISPOSED IN TELESCOPING RELATIONSHIP WITH THE RING, AFLUID CONDUIT COMMUNICATING WITH THE SECOND CYLINDER AND THE PRESSURIZEDFLUID ACTING ON THE PISTON, AND MEANS FOR URGING THE LOCK INTOENGAGEMENT WITH THE RING.